The Imperial Irrigation District sued Interior Secretary Gale Norton last week to block her from cutting the California region's share of Colorado River water by 11 percent this year, and shipping much of it to coastal cities.
The cutbacks were intended to pressure the county and California into signing a crucial deal aimed at reducing the state's over-dependence on the river that also provides water to several other fast-growing Western states.
In a letter to Imperial and three other water districts in Southern California, Assistant Interior Secretary Bennett Raley signaled the possibility of even steeper cuts in the valley's water as a result of the lawsuit.
The letter said the Interior Department has authority to take away the Imperial Valley's water on the ground that it is wasting it, citing the principle of "reasonable and beneficial use."
In what some view as a waste, one third of the valley's water winds up in the Salton Sea, a huge sump that would quickly become too salty for fish and birds if it weren't for runoff from Imperial Valley farms. Farmers say they need to use excess water, in part, to wash salt from the soil.
In the days leading up to a Dec. 31 deadline to reach the deal reducing use of the Colorado River, the Interior Department had signaled in carefully worded language that it would not consider using excess water to wash salt to be wasteful. Imperial Valley had sought the language.
Raley's letter said the water districts "should not assume that earlier drafts of relevant documents, including provisions regarding reasonable and beneficial use, will be acceptable to the United States."
The move by the Bush administration is the latest in a steadily escalating game of brinkmanship between the administration and the water board in the Imperial Valley, California's biggest user of Colorado River water. It also complicates efforts by Gov. Gray Davis to salvage the Colorado River deal and protect the state's water supply. The governor has called four Southern California water agencies to Sacramento for a round of negotiations.
The Metropolitan Water District of Southern California said hopes for a water deal seem to be fading and Imperial's lawsuit is to blame. "The real point of this is: It's a tough road to get the agreement back on track and this lawsuit just made it tougher," said Jeff Kightlinger, the MWD's general counsel.